Our “normal” body temperature of 98.6°F may not actually be normal. New research by led by Dr. Julie Parsonnet from the Stanford University School of Medicine has found that the average human body temperature is lowering slightly. The 98.6°F standard was established by a German doctor in 1851, but the new study conducted on 35,000 people found that their average was 97.9°F. Parsonnet’s study indicates that the temperature changes reflect a historical pattern, and not an error. The decrease is a result of a couple of factors such as a decline in our body's metabolic rate over the past 200 years and how climate-controlled environments that we spend majority of our lives in affect human physiology, says the study.